[PDGF-BB initiates vascular smooth muscle-like phenotype differentiation of human bone marrow mesenchymal stem cells in vitro].

OBJECTIVE: To investigate the feasibility of human bone marrow mesenchymal stem cells (hBMSCs) in vitro differentiation into vascular smooth muscle cells with induction of platelet-derived growth Factor BB (PDGF-BB). METHODS: Bone marrow mesenchymal stem cells of adult healthy donors were separated from iliac crest aspiration and expanded in DMEM-LG medium. Cells at passage 1 were transferred to EGM-2 medium containing PDGF-BB (20 ng/ml) and cultured for 14 days. The expression of SM alpha-actin, SM calponin, SMMHC and SM 22alpha were detected by immunofluorescence and observed with fluorescence microscope. mRNA expression of SMalpha-actin, SM calponin, SMMHC as well as SM 22alpha was analyzed by RT-PCR. The method of Western-Blot was applied to determine protein expression of SM 22alpha. Cells with induction were observed for the expression of SM alpha-actin,SM calponin,SMMHC by FACs analysis. RESULTS: With the induction of PDGF-BB, the morphology of cells changed to a spindle fibroblastic appearance. By fluorescence microscope observation, expression of SM alpha-actin, SM calponin and SMMHC was found intracellularly in PDGF-BB treated hBMSCs at 14 days. Western-Blot detection confirmed SM 22alpha expression by 14 days induction. RT-PCR of characteristic vascular smooth muscle cells related genes, such as SM alpha-actin, SM calponin, SMMHC and SM 22alpha revealed differentiation of vascular smooth muscle cells phenotype in monolayer culture upon stimulation with PDGF-BB for 14 days. The positive expression of SM alpha-actin, SM calponin and SMMHC in induced cells was significantly higher than that in non-induced cells (P < 0.05, n=3). CONCLUSION: These results suggested hBMSCs could be differentiated into vascular smooth muscle cell phenotype with PDGF-BB induction in vitro.

Expression pattern and preliminary functional analysis of human CREB4 gene.

cAMP response element-binding (CREB) proteins are a family of mammalian transcription activators that mediate cAMP and calcium-dependent gene expression through the cAMP response element (CRE). CREB4 is a novel member of the human CREB family. RT-PCR showed CREB4 transcripts were found in lung carcinoma LX-1, colon adenocarcinoma CX-1, prastatic adenocarcinoma PC-3, colon carcinoma G1-112, and pancreatic adenocarcinoma G1-103. Constructing CREB4 and CREB(215-395aa) fusion protein with the entire prokaryotic LexA protein respectively disclosed that CREB4 protein functioned as a transcription activator and its N-terminal accounted for the activation ability. Furthermore,a fusion protein of GFP and full-length CREB4 was localized in cytoplasm,whereas the fusion protein of GFP and a deletion mutant lacking the C-terminal putative transmembrane domain was translocated in nucleus. Our results suggested that putative transmembrane domain of CREB4 protein was associated with modulation of its function for the transcriptional activation.